External drives · Ejecting and reconnecting
What's the difference between ejecting and unmounting a drive?
Short answer: Unmounting takes one volume offline while the drive stays connected; ejecting unmounts all its volumes so the device can be unplugged. Unmount a single volume in Disk Utility, but always eject before unplugging.
Unmounting takes one volume offline so nothing can use it, while the drive stays connected. Ejecting unmounts every volume on the drive and tells macOS the whole device is about to be disconnected. Before unplugging, always eject.
Unmounting a single volume is handy when a drive has several and you only want to stop one — select it in Disk Utility and click Unmount; Mount brings it back without unplugging. For the drive Storage Studio uses, eject from Storage Studio so apps running from it are closed first — see how to eject the fast drive safely.